1. Field of the Invention
This invention relates to a key and keyway arrangement, and more particularly, to a key and keyway arrangement including a key formed from a curved wire of circular cross-section so positioned in respect to the keyway that the outside bend of the curve remains tangential to the keyway.
2. Description of the Prior Art
Standard prior art key and keyway arrangements include keys of rectangular cross-section. Such a key, however, will usually sit improperly in its associated keyway, resulting in a rocking motion of the rectangular key in the keyway and eventual failure of the key.
One prior art alternative to the rectangular cross-section is discussed in the article "Hex Key Stops Hard Rock" in Machine Design, Vol. 44, Apr. 6, 1972 at page 100. A guide arrangement comprising a two-part key of hexagonal cross-section is described wherein one part of the key is placed in the keyway between a shaft and hub, and the remaining part is driven into place to produce a compressive stress on all working faces of the key and prevent rocking motion. The hexagonal cross-section, however, is difficult to machine for keys requiring very small dimensions or cross-section.
Alternative key designs are illustrated in Machinery's Handbook-A Reference Book for the Mechanical Engineer, Draftsman, Toolmaker and Machinist, Twentieth Edition, by Erik Oberg et al at pages 991-1014. In particular, specifications for keys comprising a semicircular side view are contained therein at page 998 in Table 9, "USA Standard Woodruff Keys". As shown in the illustration associated with this table, a key possessing this semi-circular side view retains two flat sidewalls that come in contact with the sidewalls of the keyway, thereby creating the situation in which the above-described rocking motion may occur. Further, as with the hexagonal key described above, the semi-circular key is difficult to manufacture beyond a limiting key diameter requirement.
The problem remaining in the prior art, then, is to provide a key and keyway arrangement where the key comprises a configuration that eliminates the rocking motion of the key in the keyway and yet provides for simple manufacture of keys requiring very small dimensions or cross-section.